1. Field of the Invention
This invention relates to Josephson Junction devices which, upon removal of an input signal, reset themselves to a zero voltage state without interrupting the flow of gate current. It also relates to Josephson junction logic elements intended for performing logic functions at high speed. An example for the application of such logic elements is in data processing machines.
2. Description of the Prior Art
It has long been a requirement to reduce the time needed in switching operations and to increase the packing density of switching circuits so as to permit the execution of more switching operations in a certain time interval but with a yet smaller space occupied by the switching circuits. The present state of the art encompasses Josephson junction memory elements satisfying these requirements, and it is thus important to include logic circuits which can be manufactured in the same technology.
Switching circuits in Josephson junction technology so far proposed have the severe disadvantage of not being automatically resetting, thus requiring additional switches for their reset operation. While this would not pose a technical problem, the economics of any device incorporating the state of the art switching circuits must suffer considerably through long cycle times.
An example of a state of the art Josephson junction logic element is described in IBM Technical Disclosure Bulletin, Vol. 7, No. 3, August 1964, p. 271, by M. F. Merriam. A Josephson junction memory circuit is disclosed in Swiss patent 486.095. Further references of interest in connection with the invention hereafter to be described are two articles by D. E. McCumber, respectively published in the Journal of Applied Physics, Vol. 39, No. 6, May 1968, pp. 2503-8, and Vol. 39, No. 7, June 1968, pp. 3113-8, as well as the book, "Superconductive Tunneling and Applications," by L. Solymar, Chapman and Hall Ltd., London, 1972.